1. Field of the Invention
This invention relates to lathe assemblies and, more particularly, to a lathe assembly which performs a machining operation on a piece of bar stock. The invention is also directed to a method of using a lathe assembly.
2. Background Art
It is known to feed bar stock to a tool assembly and to machine the bar stock in successive machining operations to produce multiple, finished workpieces from a single piece of the bar stock. In FIGS. 1-5 herein, a conventional lathe assembly is shown at 10 for operating in this manner upon individual pieces 12 of bar stock.
The lathe assembly 10 consists of a guide 14 defining a passageway 16 within which the individual pieces 12 of bar stock can be guidingly moved selectively towards and away from a spindle 18. Through the spindle 18, the pieces 12 of bar stock can be held in a working position, as shown in FIG. 2, and rotated. A tool assembly 20 performs machining operations on the pieces 12 of bar stock in the working position to produce individual workpieces 22.
The pieces 12 of bar stock are delivered to the passageway 16 from a supply location at 24 through a feed assembly 26. The feed assembly 26 consists of an endless chain conveyor 28 which is trained around spaced pulleys 30, 32. Through a drive 34, the pulley 32 is rotated selectively in a forward direction, as indicated by the arrows 36 in FIG. 2, and a reverse direction, as indicated by the arrows 38 in FIG. 4.
A push rod 40 is attached to the upper surface of the chain conveyor 28 and is movable from left to right, with the drive 34 operated to rotate the pulley 32 in the forward direction, and from right to left, with the drive 34 operated to rotate the pulley 32 in the reverse direction. The push rod 40 has a receiver 42 at an end thereof to grip the trailing ends 44 of the pieces 12 of bar stock.
In operation, the pieces 12 of bar stock are delivered one-by-one from the supply location 24 to the top surface of the chain conveyor 28 with the push rod 40 retracted to the FIG. 1 position. The drive 32 is then activated to rotate the pulley 32 in the forward direction which causes the receiver 42 to advance from left to right and engage the trailing end 44 of the active piece 12 of bar stock. Continued operation of the drive 34 causes the leading end 46 of the active piece 12 of bar stock to be directed into and through the passageway 16 and spindle 18 to be exposed outside of the spindle 18, as shown in FIG. 2, for operation thereon by the tool assembly 20 to thereby produce a workpiece 22.
The drive 34 is incrementally operated to advance the active piece 12 of bar stock a distance equal to a predetermined length dimension for the workpiece 22. Eventually, the length of the active piece 12 of bar stock is diminished to less than the predetermined length of the workpiece 22 that is to be produced. Attempting to machine the remaining piece 12 of bar stock that is shorter than the predetermined length of the workpiece 22 could cause jamming and, in any event, is a wasted step given that the machined workpiece 22 would have to be sorted and discarded.
To avoid the above situation, it is known to use a proximity sensor 48 which detects an element 50 at the trailing end 44 of the active piece 12 of bar stock. The element 50 is strategically situated so that the proximity sensor 48 detects the element 50 once the active piece 12 of bar stock has been reduced to a length less than that necessary to form the workpiece 22. After the last possible workpiece 22 is formed, the sensor detects the element 50 and causes a signal to be generated that causes the drive 32 to thereby retract the remaining piece 12 of bar stock from the passageway 16 and release it to a disposal unit 54, as shown in FIG. 5.
The horizontal arrangement of the guide 14 is typical of conventional lathe assemblies. One problem with this horizontal arrangement is that, with very long workpieces, a significant amount of floor space may be required to operate the lathe assembly.
While it is known to vertically orient elongate workpieces held in a vertically opening chuck on lathe assemblies, the problem of chip buildup on the workpiece and chuck must be contended with.
In FIGS. 12 and 13, two additional prior art lathe assemblies are shown at 58 and 60, respectively. The lathe assembly 58 is characterized as a fixed spindle lathe assembly with there being a spindle 62 thereon, fixedly attached to a frame 63 and having a horizontal central axis 64. An elongate piece 12 of bar stock is advanced from an input end 68 of the spindle 62 through the spindle 62 to and through an output end 70 at which the piece 12 of bar stock is exposed to be machined by a tool assembly 72. The tool assembly 72 is selectively movable along X and Z axes to allow a tool element 74 on the tool assembly 72 to operate on the piece 12 of bar stock held and rotated by the spindle 62.
The lathe assembly 60 is characterized as a sliding spindle lathe assembly and includes a spindle 76 with a horizontal central axis 78. The spindle 76 has an adaptor 80 which cooperates with, and is guided along, a rail 82 on a frame 84 so as to allow the spindle 76 to move in the line of the double-headed arrow 86 parallel to the central axis 78 of the spindle 76.
In the lathe assembly 60, a bushing assembly 88 is provided with a body 90 and a bushing 92 having an opening 94 therethrough. The spindle axis 78 is coincident with the central axis for the bushing opening 94. The bushing assembly 88 serves as a support to rigidify the end of the piece 12 of bar stock that is being machined by a tool assembly 96.
Typically, both of the lathe assemblies 58, 60 are designed for relatively small diameter pieces 12 of bar stock. It is conventional to make dedicated machines that function either as a fixed spindle lathe assembly, such as the lathe assembly 58, or as a sliding spindle lathe assembly, such as the lathe assembly 60.
The invention is directed to a lathe assembly having a guide with a passageway for movement of a piece of bar stock, with a leading end and a trailing end, in a substantially straight path between a feeding position and a working position. A sensor assembly is capable of detecting the position of the trailing end of a piece of bar stock within the guide passageway to thereby allow a user to determine if a piece of bar stock in the guide passageway has a length sufficient to perform a desired operation thereon.
The lathe assembly may further include a spindle for releasably holding a piece of bar stock in the working position.
The sensor assembly may have a generator for a signal indicative that a piece of bar stock in the guide passageway has less than a predetermined length.
The lathe assembly may further include a tool assembly to perform an operation on a piece of bar stock in the working position.
The sensor assembly may include a generator for a stop signal indicative that a piece of bar stock in the guide passageway has less than the predetermined length. The lathe assembly may further include a control to receive the stop signal and, in response thereto, prevent performance of an operation by the tool assembly on a piece bar stock in the passageway.
The sensor assembly may include an elongate element that can be directed into the guide passageway to against the trailing end of a piece of bar stock in the passageway to thereby determine whether a piece of bar stock in the guide passageway is less than or greater than the predetermined length.
The sensor assembly may include a generator for a beam to be directed against the trailing end of a piece of bar stock in the guide passageway and reflected therefrom and a receiver for the reflected beam.
The generator may be a laser beam generator.
The lathe assembly may further include a piece of bar stock in the guide passageway.
The lathe assembly may still further include a drive to rotate a piece of bar stock in the working position in the guide passageway.
The tool assembly may include a tool element which acts against a piece of bar stock in the working position. The tool assembly may include a turret with a plurality of interchangeable tool elements.
In one form, the spindle has an axis and axially spaced input and output ends and the piece of bar stock in the working position projects from both the input and output ends of the spindle.
In one form, the passageway has a central axis and axially spaced first and second ends. The spindle is at the first axially spaced end and the second axially spaced end is open to allow introduction of a piece of bar stock into the guide passageway.
The invention is also directed to a method of operating a lathe assembly having a guide with a passageway with a central axis and axially spaced first and second ends, a spindle, and a tool assembly for performing an operation on a piece of bar stock having a length and leading and trailing ends. The method includes the steps of directing a piece of bar stock axially through the guide passageway in a first direction from a feeding position into a working position and directing an element into the guide passageway to detect the position of the trailing end of the piece of bar stock and thereby determine if the piece of bar stock in the guide passageway is less than or greater than the predetermined length.
The method may further include the step of performing an operation on the piece of bar stock with the tool assembly if it is determined that the piece of bar stock has at least the predetermined length.
The method may further include the step of advancing the piece of bar stock in the first direction after performing the operation and again directing the element into the guide passageway to detect the position of the trailing end of the piece of bar stock to again determine if the piece of bar stock in the guide passageway is less than or greater than the predetermined length.
The step of directing an element from the sensor into the guide passageway may involve the step of directing a laser beam into the guide passageway.
The step of directing an element from the sensor into the guide passageway may involve the step of directing an elongate element into the guide passageway.
The method may further include the steps of providing a sensor assembly, generating a stop signal from the sensor assembly indicative that the piece of bar stock has a length less than the predetermined length, and processing the stop signal so that no operation is performed by the tool assembly on the piece of bar stock in the guide passageway.
The invention is also directed to a lathe assembly with a guide having a passageway with a central axis for movement of a piece of bar stock with a leading end and trailing end in a substantially straight path substantially parallel to the central axis of the passageway between a feeding position and a working position, and a spindle for releasably holding a piece of bar stock in the working position and having a through opening with a central axis, an input end, and an output end. The guide is oriented so that the central axis of the passageway is not parallel to a horizontal support surface for the lathe assembly. The passageway and through opening are aligned so that the leading end of a piece of bar stock can move through the passageway to and through the through opening from the input end to the output end to project from the output end with a piece of bar stock in the working position.
The central axes of the passageway and through opening may be substantially parallel to each other and extend substantially orthogonally to a horizontal support surface for the lathe assembly.
In one form, the central axes of the passageway and through opening are substantially parallel to each other and are non-orthogonal to a horizontal support surface for the lathe assembly.
The lathe assembly may further include a tool assembly for performing an operation on a piece of bar stock in the working position.
The invention is also directed to a method of operating a lathe assembly with a guide having a passageway with a central axis and axially spaced first and second ends, a spindle with a through opening having a central axis, an input end and an output end, and a tool assembly for performing an operation on a piece of bar stock having a length, a leading end, and a trailing end. The method includes the steps of orienting the guide so that the central axis of the passageway is inclined relative to a horizontal support surface for the lathe assembly and so that the central axis of the passageway declines from the first end towards the second end of the passageway, directing the leading end of the piece of bar stock into and through the passageway in a first direction from the first end of the passageway towards the second end of the passageway, moving the leading end of the piece of bar stock in the first direction into and through the through opening to a working position wherein the leading end of the bar stock projects from the output end of the spindle, clamping the piece of bar stock in the working position in the spindle, and performing an operation on a portion of the piece of bar stock projecting from the output end of the through opening with the piece of bar stock in the working position.
The method may further include the steps of placing a plurality of pieces of bar stock, each having a length, in a storage position, with the lengths of the plurality of pieces of bar stock being substantially parallel to each other and substantially parallel to a horizontal surface supporting the lathe assembly, removing the plurality of workpieces of bar stock one-by-one from the storage position, and directing the plurality of pieces of bar stock one-by-one into the passageway.
The method may further include the steps of placing a plurality of pieces of bar stock each having a length in a storage position with the lengths of the plurality of pieces of bar stock being substantially parallel to each other and substantially non-parallel to a horizontal surface supporting the lathe assembly, removing the plurality of pieces of bar stock one-by-one from the storage position, and directing the plurality of pieces of bar stock one-by-one into the passageway.
The invention is further directed to a lathe assembly having a spindle for holding an elongate workpiece and having a central axis, and a guide assembly having a body and a guide bushing on the body having a first opening with a central axis. The spindle and guide assembly are selectively repositionable between a) a first relative position wherein the central axis of the spindle extends through the first guide bushing opening so that an elongate workpiece held by the spindle can be projected into the first guide bushing opening so that the guide bushing limits flexing of an elongate workpiece held by the spindle and b) a second relative position wherein the central axis of the spindle does not extend through the first guide bushing opening. The lathe assembly further includes a tool assembly for performing an operation on an elongate workpiece held by the spindle.
In one form, with the spindle and guide assembly in the first relative position, the central axis of the spindle is substantially coincident with the central axis of the first guide bushing opening.
The guide bushing may be rotatable relative to the guide assembly body around the central axis of the first guide bushing opening.
The lathe assembly may further be provided in combination with an elongate workpiece that is held by the spindle and projects into the first guide bushing opening with the spindle and guide assembly in the first relative position.
In one form, the guide assembly has a second opening in the body with a central axis and with the spindle and the guide assembly in the second relative position, the central axis of the spindle extends through the second opening.
In one form, the first guide bushing opening has a first diameter, and the second opening has a second diameter, and the first diameter is different than the second diameter.
The guide assembly may be translatable relative to the spindle as the spindle and guide assembly are repositioned between the first relative position and the second relative position.
The guide assembly may be rotatable about an axis relative to the spindle as the spindle and guide assembly are repositioned between the first relative position and the second relative position.
The spindle and guide assembly may be movable, one relative to the other, along a line substantially parallel to the central axis of the spindle.
In one form, the spindle is abuttable to the guide assembly to be supported by the guide assembly.
In one form, with the spindle and the guide assembly in the second relative position, the central axis of the spindle is substantially coincident with the central axis of the second opening.